1. Field of the Invention
The present invention relates generally to a beam projector, and more particularly to a focusing device for a compact and portable beam projector.
2. Description of the Related Art
A beam projector generally refers to a device for implementing an image on a display device, and transmitting light generated from an additional light source into a display device and projecting the transmitted light on a screen to provide the image. The light transmitted through the display device can be expanded through a lens assembly and the focus of light can be adjusted based on a distance of the lens from a screen.
Such a beam projector can easily control a size of an image. However, as the image is magnified, the image quality deteriorates and the colors are not accurately depicted in some lighted areas. Some of these disadvantages have been overcome by recent technology for manufacturing the display device and the lens system.
Since the beam projector is an expensive device, it has been almost exclusively used in conferences, report presentations, assemblies, or public events in such places as a large conference room, and has not enjoyed much use by the typical consumer. However, a home beam projector has been recently commercialized, and with the development of information devices such as portable terminals, an effort has been made to commercialize a highly portable and pocket-sized beam projector.
Image quality through the beam projector greatly depends on the quality of the display device, light source, and lens system. However, the quality of an image implemented through a pre-manufactured beam projector depends on an appropriate distance between a screen and a beam projector and the focus adjustment in an installation state.
There is a limitation in installing a focusing device in a beam projector mounted on a portable terminal or a pocket-sized beam projector. That is, since the beam projector is conventionally used in such large areas as a conference room, the focusing device is constructed to be remotely controlled using a gear or motor. However, it is exceedingly difficult to install such a focusing device for pocket-sized portability purposes or retro-fit such a focusing device on an already manufactured beam projector.